Many types of equipment such as but not limited to baseball bats, softball bats, golf clubs, tennis racquets, hammers, pickaxes, and sledgehammer generally include a handle which is gripped by the hands at the proximal end, and a weighted object at the distal end of the handle. The weighted object may be incorporated into the handle (e.g., a barrel of a baseball bat that is integrally formed with the baseball bat handle) or may be a separate element attached to the handle (e.g., head of a hammer that is attached to a handle). The act of swinging weighted, club-like equipment in a circular or elliptical trajectory generates several dynamic forces.
More specifically, turning forces result because a spinning object such as a baseball bat swung in a circular or elliptical trajectory has angular momentum and resists a change in direction. Also, during the swing centrifugal force is created such as when the barrel of the baseball bat or golf club is pulled away from the body and centripetal force is generated to pull the weighted object proximal to the body. Because of these forces it is necessary for the user to tightly grip the handle with their hands to hold on to the equipment.
A tight hand grip can result in multiple negative consequences. For example, one negative consequence of tight hand grip during a swing is the generation of friction between the skin of the hands and the handle. Friction results from the force of the weighted equipment which pull the equipment away from the body, and the force created when the bat handle moves due to opposing forces to pull the handle towards the body. Therefore, the user tightens the hand grip to hold on to the handle which prevents the forces from causing the equipment to fly out of their hands.
Another negative consequence of tight hand grip during a swing is injury to the hands. Friction from repetitive swings using known, traditional equipment can result in skin blisters. Further, tight hand grip during a swing may result in injury to the user's hand bones. Specifically, bruising and fracture of the tricumvarate, pisiform, and hamate bones in the hand results from pressure generated against a narrow surface area of the hand in contact with the swinging equipment. Also, damage to the ulnar nerve in the hand may occur when the forces generated during a swing of weighted equipment are transmitted to a narrow surface area on the hand. This damage may result in loss of grip during a swing and the equipment being thrown from the hand.
A third negative consequence of tightened hand grip is decreased swing velocity. Tight hand grip promotes slower swing speed because of large muscle contraction. Slower swing speed decreases impact and results in less force for hitting an object, such as a baseball, nail, or a golf ball. Tight hand grip can also produce less precision due to the aforementioned loss of fine motor muscle use in the hands.